1. Field of the Invention
The present invention relates to machines used to grind skis, particularly their lower running surface.
2. Description of the Prior Art
Such machines are generally used to repair the bottoms of skis. The grinding operation may take place after resurfacing by overmoulding the running bottom.
Ski grinding machines in current use are generally machines having an abrasive belt consisting of a frame that stands on the floor and supports the functional units of the machine, a support drum mounted rotatably around a first horizontal axis, forming an accessible support area to accommodate the surface of the ski to be ground, a return drum mounted rotatably around a second horizontal axis offset with respect to the first axis and an abrasive belt stretched between the support drum and the return drum. Tensioning means pull at least one of the drums away from the other drum in order to tension the abrasive belt. Driving means are used to drive the support drum and abrasive belt. A system for circulating water sprays jets of water onto the area of the abrasive belt surrounding the support drum and collects the water that flows on the abrasive belt after it has passed through the machining area.
The abrasive belt is generally sufficiently wide to grind an alpine ski, i.e. its width is approximately 10 to 20 cm inclusive.
A similar technique is described in documents DE-A-2 502 718 and U.S. Pat. No. 2,827,935 for the machining of panels: the panels pass between an upper driving drum and a portion of an abrasive belt that surrounds a lower support drum.
In document U.S. Pat. No. 4,137,673, an abrasive belt is stretched between two rollers and forms a support sheet supported by a deformable mounting. The ski is machined by the support sheet and is driven by the driving rollers.
Machines that are usually used are, however, not wide enough to allow the entire width of a snow board to be ground in a single pass over the belt.
In addition, it seems that the grinding thus obtained does not always produce an adequate surface finish in terms of flatness and surface roughness. To achieve this, for example in document FR-A-2 614 819, special grinding machines having a grinding wheel or rigid drum have already been proposed. Such grinding by a grinding wheel is generally referred to as "dry grinding" and ensures flattening of the lower surface of the ski. It is then necessary to combine, in several passes on different machines, one or more grinding operations using an abrasive belt and at least one "dry grinding" operation. Each pass involves adjusting the belt speed, the feed speed of the ski in the machine and the pressure of the ski against the abrasive belt or grinding wheel. Results largely depend on the skill of the user and are inconsistent. This solution is therefore unsatisfactory in technical terms. In addition, the use of several machines significantly increases production costs, requires considerable space, complicates handling and experience shows that such complication is prohibitive for sports shops and persons who hire out ski equipment who often tend to make do with an abrasive-belt machine.